1. Field
Apparatus consistent with exemplary embodiments relate to an optical modulator and a 3D image acquisition apparatus including an optical modulator, and more particularly, to an optical modulator generating optical confinement and a 3D image acquisition apparatus including an optical modulator generating optical confinement.
2. Description of the Related Art
Conventional 3D cameras, comprising conventional image shooting functions, incorporate a measuring function for measuring the distance between a plurality of points on the surface of a subject and the camera. At present, several algorithms are available for measuring the distance between a subject and a 3D camera, among which the Time-of-Flight (TOF) method is widely used. The TOF method incorporates projecting an illumination signal at a subject and measuring the flight time for the illumination reflect from the subject, and arrive back at a receiving unit. The flight time of the illumination signal may be measured by a phase delay. Furthermore, a high-speed optical modulator may be used for an accurate measurement of the phase delay.
The characteristic of transmittance difference of an optical modulator (optical shutter), which is used to obtain the depth information in a 3D camera, is the most important factor in 3D image realization because a bigger transmittance difference enables an improved accuracy and a higher 3D image quality.
Transmittance difference is the difference in the transmittance due to a quantum-confined Stark effect (QCSE) of a particular wave depending on whether voltage is applied to the optical modulator. When the voltage is not applied to the optical modulator, the optical modulator enters a shutter-open status, and when the voltage is applied to the optical modulator, the transmission-type optical modulator enters a shutter-close status. Therefore, by decreasing the transmissivity when the voltage is not applied or increasing the transmissivity when the voltage is applied, the transmittance difference of the optical modulator may be enhanced. Particularly, decreasing the transmissivity when the voltage is not applied may enhance the quality of the 3D image.